Im looking to buy a co-op game on the xbox 360 for my little brother and I to play. He lives in New Jersey and I'm in California so we can't just hit the local store. I'm buying both games since he is still young and has no money to spend. Since i can buy codes off amazon and give them him over the phone its perfect.

So whats a good online co-op game on the xbox 360 marketplace? I want it to be a deep enough game and keep us engaged to get through together. Please no military shooters or board games. He is 13 and I'm 21.